Protease-activated receptor-1 contributes to cardiac remodeling and hypertrophy

Beyond Anticoagulation: A Comprehensive Review of Non-Vitamin K Oral Anticoagulants (NOACs) in Inflammation and Protease-Activated Receptor Signaling

Non-vitamin K oral anticoagulants (NOACs) have revolutionized anticoagulant therapy, offering improved safety and efficacy over traditional agents like warfarin. This review comprehensively examines the dual roles of NOACs-apixaban, rivaroxaban, edoxaban, and dabigatran-not only as anticoagulants, but also as modulators of inflammation via protease-activated receptor (PAR) signaling. We highlight the unique pharmacotherapeutic properties of each NOAC, supported by key clinical trials demonstrating their effectiveness in preventing thromboembolic events. Beyond their established anticoagulant roles, emerging research suggests that NOACs influence inflammation through PAR signaling pathways, implicating factors such as factor Xa (FXa) and thrombin in the modulation of inflammatory responses. This review synthesizes current evidence on the anti-inflammatory potential of NOACs, exploring their impact on inflammatory markers and conditions like atherosclerosis and diabetes. By delineating the mechanisms by which NOACs mediate anti-inflammatory effects, this work aims to expand their therapeutic utility, offering new perspectives for managing inflammatory diseases. Our findings underscore the broader clinical implications of NOACs, advocating for their consideration in therapeutic strategies aimed at addressing inflammation-related pathologies. This comprehensive synthesis not only enhances understanding of NOACs' multifaceted roles, but also paves the way for future research and clinical applications in inflammation and cardiovascular health.

Improving iPSC Differentiation Using a Nanodot Platform

Differentiation of induced pluripotent stem cells (iPSCs) is an extremely complex process that has proven difficult to study. In this research, we utilized nanotopography to elucidate details regarding iPSC differentiation by developing a nanodot platform consisting of nanodot arrays of increasing diameter. Subjecting iPSCs cultured on the nanodot platform to a cardiomyocyte (CM) differentiation protocol revealed several significant gene expression profiles that were associated with poor differentiation. The observed expression trends were used to select existing small-molecule drugs capable of modulating differentiation efficiency. BRD K98 was repurposed to inhibit CM differentiation, while iPSCs treated with NSC-663284, carmofur, and KPT-330 all exhibited significant increases in not only CM marker expression but also spontaneous beating, suggesting improved CM differentiation. In addition, quantitative polymerase chain reaction was performed to determine the gene regulation responsible for modulating differentiation efficiency. Multiple genes involved in extracellular matrix remodeling were correlated with a CM differentiation efficiency, while genes involved in the cell cycle exhibited contrasting expression trends that warrant further studies. The results suggest that expression profiles determined via short time-series expression miner analysis of nanodot-cultured iPSC differentiation can not only reveal drugs capable of enhancing differentiation efficiency but also highlight crucial sets of genes related to processes such as extracellular matrix remodeling and the cell cycle that can be targeted for further investigation. Our findings confirm that the nanodot platform can be used to reveal complex mechanisms behind iPSC differentiation and could be an indispensable tool for optimizing iPSC technology for clinical applications.

Direct interrogation of context-dependent GPCR activity with a universal biosensor platform

G protein-coupled receptors (GPCRs) are the largest family of druggable proteins encoded in the human genome, but progress in understanding and targeting them is hindered by the lack of tools to reliably measure their nuanced behavior in physiologically relevant contexts. Here, we developed a collection of compact ONE vector G-protein Optical (ONE-GO) biosensor constructs as a scalable platform that can be conveniently deployed to measure G-protein activation by virtually any GPCR with high fidelity even when expressed endogenously in primary cells. By characterizing dozens of GPCRs across many cell types like primary cardiovascular cells or neurons, we revealed insights into the molecular basis for G-protein coupling selectivity of GPCRs, pharmacogenomic profiles of anti-psychotics on naturally occurring GPCR variants, and G-protein subtype signaling bias by endogenous GPCRs depending on cell type or upon inducing disease-like states. In summary, this open-source platform makes the direct interrogation of context-dependent GPCR activity broadly accessible.

Direct interrogation of context-dependent GPCR activity with a universal biosensor platform

G protein-coupled receptors (GPCRs) are the largest family of druggable proteins in the human genome, but progress in understanding and targeting them is hindered by the lack of tools to reliably measure their nuanced behavior in physiologically-relevant contexts. Here, we developed a collection of compact ONE vector G-protein Optical (ONE-GO) biosensor constructs as a scalable platform that can be conveniently deployed to measure G-protein activation by virtually any GPCR with high fidelity even when expressed endogenously in primary cells. By characterizing dozens of GPCRs across many cell types like primary cardiovascular cells or neurons, we revealed new insights into the molecular basis for G-protein coupling selectivity of GPCRs, pharmacogenomic profiles of anti-psychotics on naturally-occurring GPCR variants, and G-protein subtype signaling bias by endogenous GPCRs depending on cell type or upon inducing disease-like states. In summary, this open-source platform makes the direct interrogation of context-dependent GPCR activity broadly accessible.

The Role of Tissue Factor In Signaling Pathways of Pathological Conditions and Angiogenesis

Tissue factor (TF) is an integral transmembrane protein associated with the extrinsic coagulation pathway. TF gene expression is regulated in response to inflammatory cytokines, bacterial lipopolysaccharides, and mechanical injuries. TF activity may be affected by phosphorylation of its cytoplasmic domain and alternative splicing. TF acts as the primary initiator of physiological hemostasis, which prevents local bleeding at the injury site. However, aberrant expression of TF, accompanied by the severity of diseases and infections under various pathological conditions, triggers multiple signaling pathways that support thrombosis, angiogenesis, inflammation, and metastasis. Protease-activated receptors (PARs) are central in the downstream signaling pathways of TF. In this study, we have reviewed the TF signaling pathways in different pathological conditions, such as wound injury, asthma, cardiovascular diseases (CVDs), viral infections, cancer and pathological angiogenesis. Angiogenic activities of TF are critical in the repair of wound injuries and aggressive behavior of tumors, which are mainly performed by the actions of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 (HIF1-α). Pro-inflammatory effects of TF have been reported in asthma, CVDs and viral infections, including COVID-19, which result in tissue hypertrophy, inflammation, and thrombosis. TF-FVII induces angiogenesis via clotting-dependent and -independent mechanisms. Clottingdependent angiogenesis is induced via the generation of thrombin and cross-linked fibrin network, which facilitate vessel infiltration and also act as a reservoir for endothelial cells (ECs) growth factors. Expression of TF in tumor cells and ECs triggers clotting-independent angiogenesis through induction of VEGF, urokinase-type plasminogen activator (uPAR), early growth response 1 (EGR1), IL8, and cysteine-rich angiogenic inducer 61 (Cyr61).

Coagulation Factor Xa Has No Effects on the Expression of PAR1, PAR2, and PAR4 and No Proinflammatory Effects on HL-1 Cells

Atrial fibrillation (AF), characterised by irregular high-frequency contractions of the atria of the heart, is of increasing clinical importance. The reasons are the increasing prevalence and thromboembolic complications caused by AF. So-called atrial remodelling is characterised, among other things, by atrial dilatation and fibrotic remodelling. As a result, AF is self-sustaining and forms a procoagulant state. But hypercoagulation not only appears to be the consequence of AF. Coagulation factors can exert influence on cells via protease-activated receptors (PAR) and thereby the procoagulation state could contribute to the development and maintenance of AF. In this work, the influence of FXa on Heart Like-1 (HL-1) cells, which are murine adult atrial cardiomyocytes (immortalized), was investigated. PAR1, PAR2, and PAR4 expression was detected. After incubations with FXa (5-50 nM; 4-24 h) or PAR1- and PAR2-agonists (20 µM; 4-24 h), no changes occurred in PAR expression or in the inflammatory signalling cascade. There were no time- or concentration-dependent changes in the phosphorylation of the MAP kinases ERK1/2 or the p65 subunit of NF-κB. In addition, there was no change in the mRNA expression of the cell adhesion molecules (ICAM-1, VCAM-1, fibronectin). Thus, FXa has no direct PAR-dependent effects on HL-1 cells. Future studies should investigate the influence of FXa on human cardiomyocytes or on other cardiac cell types like fibroblasts.

Mannose binding lectin-associated serine protease-1 is a novel contributor to myocardial ischemia/reperfusion injury

BACKGROUND

The lectin pathway has been demonstrated to play a critical role in the pathological process of myocardial ischemia/reperfusion injury (IRI). Mannose-binding lectin (MBL)-associated serine protease-1 (MASP-1), especially different from other components of the lectin pathway, mediates proinflammatory and procoagulant reactions independent of complement cascades. However, the role of MASP-1 in myocardial IRI remains unknown so far.

METHODS

Myocardial IRI was established with 45 min ischemia and 24 h reperfusion in mice. C1 inhibitor, as the natural inhibitor of MASP-1, was administrated at 20 IU/Kg via tail vein 5 min before surgical operation. Cardiac function and myocardial infarct size were assessed. Myocardial histology and fibrosis were evaluated by H&E and Masson staining, respectively. Deposition of MASP-1, expression of PAR-1/4 and neutrophil extracellular traps (NET) were investigated on myocardium tissue by IHC staining. Cell apoptosis was detected by TUNEL assay. Levels of myocardial enzymes and proinflammatory cytokines were determined by ELISA.

RESULTS

Inhibition of MASP-1 with C1 INH improved cardiac function and alleviated myocardium tissue injury (infarct size, enzymes, histology and fibrosis) after myocardial IRI. Deposition of MASP-1 and expression PAR-1, as well as NET formation in myocardial tissue were suppressed by MASP-1 inhibitor, while PAR-4 was elevated. Levels of apoptosis, HMGB-1 and IL-6 were lower after blocking MASP-1. Yet, IL-8 and TNF-α remained unchanged.

CONCLUSIONS

MASP-1, as a new contributor, played a critical role in myocardial IRI. Inhibition of MASP-1 protected myocardial tissue from IRI probably via regulation of PARs/NET pathway. This may provide a novel target strategy against myocardial IRI.

Suppression of Heart Failure With PAR1 Pepducin Technology in a Pressure Overload Model in Mice

BACKGROUND

PAR1 (protease-activated receptor-1) contributes to acute thrombosis, but it is not clear whether the receptor is involved in deleterious inflammatory and profibrotic processes in heart failure. Here, we employ the pepducin technology to determine the effects of targeting PAR1 in a mouse heart failure with reduced ejection fraction model.

METHODS

After undergoing transverse aortic constriction pressure overload or sham surgery, C57BL/6J mice were randomized to daily sc PZ-128 pepducin or vehicle, and cardiac function, inflammation, fibrosis, and molecular analyses conducted at 7 weeks RESULTS: After 7 weeks of transverse aortic constriction, vehicle mice had marked increases in macrophage/monocyte infiltration and fibrosis of the left ventricle as compared with Sham mice. PZ-128 treatment significantly suppressed the inflammatory cell infiltration and cardiac fibrosis. Despite no effect on myocyte cell hypertrophy, PZ-128 afforded a significant reduction in overall left ventricle weight and completely protected against the transverse aortic constriction-induced impairments in left ventricle ejection fraction. PZ-128 significantly suppressed transverse aortic constriction-induced increases in an array of genes involved in myocardial stress, fibrosis, and inflammation.

CONCLUSIONS

The PZ-128 pepducin is highly effective in protecting against cardiac inflammation, fibrosis, and loss of left ventricle function in a mouse model.

Emerging roles of protease-activated receptors in cardiometabolic disorders

Cardiometabolic disorders, including obesity-related insulin resistance and atherosclerosis, share sterile chronic inflammation as a major cause; however, the precise underlying mechanisms of chronic inflammation in cardiometabolic disorders are not fully understood. Accumulating evidence suggests that several coagulation proteases, including thrombin and activated factor X (FXa), play an important role not only in the coagulation cascade but also in the proinflammatory responses through protease-activated receptors (PARs) in many cell types. Four members of the PAR family have been cloned (PAR 1-4). For instance, thrombin activates PAR-1, PAR-3, and PAR-4. FXa activates both PAR-1 and PAR-2, while it has no effect on PAR-3 or PAR-4. Previous studies demonstrated that PAR-1 and PAR-2 activated by thrombin or FXa promote gene expression of inflammatory molecules mainly via the NF-κB and ERK1/2 pathways. In obese adipose tissue and atherosclerotic vascular tissue, various stresses increase the expression of tissue factor and procoagulant activity. Recent studies indicated that the activation of PARs in adipocytes and vascular cells by coagulation proteases promotes inflammation in these tissues, which leads to the development of cardiometabolic diseases. This review briefly summarizes the role of PARs and coagulation proteases in the pathogenesis of inflammatory diseases and describes recent findings (including ours) on the potential participation of this system in the development of cardiometabolic disorders. New insights into PARs may ensure a better understanding of cardiometabolic disorders and suggest new therapeutic options for these major health threats.

The protective effect of rivaroxaban with or without aspirin on inflammation, oxidative stress, and platelet reactivity in isoproterenol-induced cardiac injury in rats

Coronary artery diseases are principal sources of mortality and disability in global human population. Progressively, rivaroxaban is being evaluated for the prevention of atherosclerotic thrombi, particularly with anti-platelet agents. Hence, the current report aimed to investigate the cardioprotective effect of rivaroxaban on isoproterenol (ISO)-induced cardiac injury model in rats and the possible synergistic effect when combined with aspirin. Male Wistar rats were randomly assigned into five different groups. Cardiac injury was induced by subcutaneous injection of ISO (85 mg/kg) for 2 consecutive days. Rat tail bleeding time was performed prior to sacrifice. Cardiac enzymes, platelet activity, inflammatory, and oxidative stress biomarkers levels were measured using enzyme-linked immunoassay (ELISA). Pre-administration of rivaroxaban alone and on combination with aspirin prevented ISO-induced increase in cardiac thiobarbituric acid reactive substances (TBARS), interleukin 6 (IL-6), and thromboxane B2 (TXB2) levels. Moreover, a significant prolongation of bleeding time was demonstrated among aspirin, rivaroxaban, and aspirin plus rivaroxaban treated groups. On the other hand, the combination treatment of aspirin plus rivaroxaban showed no marked difference in these biomarkers and bleeding time relative to either drug administered separately. However, a prominent decrease of cardiac 6-keto prostaglandin F1α (6-Keto-PGF1α) level was displayed in the combination treatment when compared with ISO and rivaroxaban-treated groups, whereas no significant improvement was seen in cardiac glycoprotein V (GPV) levels except in aspirin-treated group. The study results demonstrated that rivaroxaban decreases cardiac oxidative stress, inflammation, and platelets reactivity. However, the addition of rivaroxaban to aspirin did not seem to show synergistic antioxidant, anti-inflammatory, or antiplatelet effect.

Elevated serum PAR-1 levels as an emerging biomarker of inflammation to predict the dengue infection severity

The present study was designed to check the serum levels of protease-activated receptor (PAR-1) in patients during different phases of dengue severity. Moreover, a correlation between serum PAR-1 levels and hematological parameters, inflammatory cytokine levels, and liver functional changes was also determined. Based on the World Health Organization criteria, the study population was divided into: nonsevere dengue fever (DF; n = 30), severe dengue hemorrhagic fever (DHF; n = 19), and severe dengue shock syndrome (DSS; n = 11). The platelet count (PLT) and hematocrit (HCT) were analyzed using an automated hematology analyzer and liver function enzymes aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphate (ALP), bilirubin were checked by auto-analyzer using diagnostic kits. Moreover, the levels of inflammatory mediators C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-17 (IL-17), and PAR-1 were determined using respective ELISA kits. The HCT levels were elevated and platelet count decreased significantly during dengue complications (DHF and DSS) compared to the DF patients, while the levels of liver functional biomarkers AST, ALT, ALP, and bilirubin remained elevated in DHF and DSS groups than in the corresponding DF group. Similarly, the inflammatory cytokine levels of CRP, TNF-α, IL-6, and IL-17 in DHF and DSS subjects were markedly increased when observed against DF subjects. Notably, the PAR-1 levels were significantly elevated in DHF and DSS groups than in the DF group and positively correlated with changes in HCT levels, inflammatory biomarkers, and liver enzymes. Our findings conclude that PAR-1 levels persistently increased with the severity of the dengue infection and are strongly associated with various clinical manifestations. Thus, PAR-1 levels can be used as a diagnostic marker for assessing dengue severity.

Protease-activated receptors in health and disease

Proteases are signaling molecules that specifically control cellular functions by cleaving protease-activated receptors (PARs). The four known PARs are members of the large family of G protein-coupled receptors. These transmembrane receptors control most physiological and pathological processes and are the target of a large proportion of therapeutic drugs. Signaling proteases include enzymes from the circulation; from immune, inflammatory epithelial, and cancer cells; as well as from commensal and pathogenic bacteria. Advances in our understanding of the structure and function of PARs provide insights into how diverse proteases activate these receptors to regulate physiological and pathological processes in most tissues and organ systems. The realization that proteases and PARs are key mediators of disease, coupled with advances in understanding the atomic level structure of PARs and their mechanisms of signaling in subcellular microdomains, has spurred the development of antagonists, some of which have advanced to the clinic. Herein we review the discovery, structure, and function of this receptor system, highlight the contribution of PARs to homeostatic control, and discuss the potential of PAR antagonists for the treatment of major diseases.

PARs in the inflammation-cancer transformation of CRC

Colorectal cancer (CRC) is one of the common malignancies with a global trend of increasing incidence and mortality. There is an urgent need to identify new predictive markers and therapeutic targets for the treatment of CRC. Protease-activated receptors (PARs) are a class of G-protein-coupled receptors, with currently identified subtypes including PAR1, PAR2, PAR3 and PAR4. Increasingly, studies suggest that PARs play an important role in the growth and metastasis of CRC. By targeting multiple signaling pathways may contribute to the pathogenesis of CRC. In this review, we first describe recent studies on the role of PARs in CRC inflammation-cancer transformation, focusing on the important role of PARs in signaling pathways associated with inflammation-cancer transformation, and summarize the progress of research on PARs-targeted drugs.

Advances in research on the protective mechanisms of traditional Chinese medicine (TCM) in myocardial ischaemia-reperfusion injury

CONTEXT

Developing effective drugs to treat myocardial ischaemia-reperfusion (MI/R) injury is imperative. Traditional Chinese medicines (TCMs) have had considerable success in the treatment of cardiovascular diseases. Elucidating the mechanisms by which TCMs improve MI/R injury can supplement the literature on MI/R prevention and treatment.

OBJECTIVE

To summarise TCMs and their main protective mechanisms against MI/R injury reported over the past 40 years.

METHODS

Relevant literature published between 1980 and 2020 in Chinese and English was retrieved from the Web of Science, PubMed, SpringerLink, PubMed Central, Scopus, and Chinese National Knowledge Infrastructure (CNKI) databases. Search terms included 'medicinal plants', 'myocardial ischaemia reperfusion injury', 'Chinese medicine prescriptions', 'mechanisms', 'prevention', 'treatment' and 'protection'. For inclusion in the analysis, medicinal plants had to be searchable in the China Medical Information Platform and Plant Database.

RESULTS

We found 71 medicinal species (from 40 families) that have been used to prevent MI/R injury, of which Compositae species (8 species) and Leguminosae species (7 species) made up the majority. Most of the effects associated with these plants are described as antioxidant and anti-inflammatory. Furthermore, we summarised 18 kinds of Chinese compound prescriptions, including the compound Danshen tablet and Baoxin pill, which mainly reduce oxidative stress and regulate mitochondrial energy metabolism.

DISCUSSION AND CONCLUSIONS

We summarised TCMs that protect against MI/R injury and their pharmacological mechanisms. This in-depth explanation of the roles of TCMs in MI/R injury protection provides a theoretical basis for the research and development of TCM-based treatment drugs.

Mechanisms and Drug Intervention for Doxorubicin-Induced Cardiotoxicity Based on Mitochondrial Bioenergetics

Doxorubicin (DOX) is an anthracycline chemotherapy drug, which is indispensable in antitumor therapy. However, its subsequent induction of cardiovascular disease (CVD) has become the primary cause of mortality in cancer survivors. Accumulating evidence has demonstrated that cardiac mitochondrial bioenergetics changes have become a significant marker for doxorubicin-induced cardiotoxicity (DIC). Here, we mainly summarize the related mechanisms of DOX-induced cardiac mitochondrial bioenergetics disorders reported in recent years, including mitochondrial substrate metabolism, the mitochondrial respiratory chain, myocardial ATP storage and utilization, and other mechanisms affecting mitochondrial bioenergetics. In addition, intervention for DOX-induced cardiac mitochondrial bioenergetics disorders using chemical drugs and traditional herbal medicine is also summarized, which will provide a comprehensive process to study and develop more appropriate therapeutic strategies for DIC.

Serum protease-activated receptor (PAR-1) levels as a potential biomarker for diagnosis of inflammation in type 2 diabetic patients

BACKGROUND

Inflammation is a prominent clinical manifestation in type 2 diabetes mellitus (T₂DM) patients, often associated with insulin resistance, metabolic dysregulation, and other complications.

AIM OF THE STUDY

The present study has been designed to check the serum levels of PAR-1 and correlate with various clinical manifestations and inflammatory cytokines levels in type 2 diabetic subjects.

MATERIAL AND METHODS

The study population was divided into two groups, healthy volunteers (n = 15): normal glycated hemoglobin (HbA1c) (4.26 ± 0.55) and type 2 diabetic subjects (n = 30): HbA1c levels (7.80 ± 2.41). The serum levels of PAR-1 (ELISA method) were studied in both groups and correlated with demographic parameters age, weight, body mass index (BMI), and conventional inflammation biomarkers like C-reactive protein (CRP), interleukin 6 (IL-6), interleukin 8 (IL-8), and tumour necrosis factor-alpha (TNF-α).

RESULTS

The demographic variables including the body weight (77.38 ± 10.00 vs. controls 55.26 ± 6.99), BMI (29.39 ± 3.61 vs. controls 25.25 ± 4.01), glycemic index HbA1c (7.80 ± 2.41 vs. controls 4.26 ± 0.55) were found to be statistically increased in T₂DM subjects than the healthy control group. The levels of various inflammatory biomarkers and PAR-1 were significantly elevated in T₂DM groups in comparison to healthy volunteers. The univariate and multivariate regression analysis revealed that elevated PAR-1 levels positively correlated with increased body weight, BMI, HbA1c, and inflammatory cytokines.

CONCLUSION

Our findings indicate that the elevated serum PAR-1 levels serve as an independent predictor of inflammation in T₂DM subjects and might have prognostic value for determining T₂DM progression.

From Iron Metabolism to Ferroptosis: Pathologic Changes in Coronary Heart Disease

Coronary heart disease (CHD) is closely related to oxidative stress and inflammatory response and is the most common cardiovascular disease (CVD). Iron is an essential mineral that participates in many physiological and biochemical reactions in the human body. Meanwhile, on the negative side, iron has an active redox capacity, which leads to the accumulation of reactive oxygen species (ROS) and lipid peroxidation. There is growing evidence that disordered iron metabolism is involved in CHD's pathological progression. And the result of disordered iron metabolism is associated with iron overload-induced programmed cell death, often called ferroptosis. That features iron-dependent lipid peroxidation. Ferroptosis may play a crucial role in the development of CHD, and targeting ferroptosis may be a promising option for treating CHD. Here, we review the mechanisms of iron metabolism in cardiomyocytes (CMs) and explain the correlation between iron metabolism and ferroptosis. Meanwhile, we highlight the specific roles of iron metabolism and ferroptosis in the main pathological progression of CHD.

The Therapeutic Potential of Anticoagulation in Organ Fibrosis

Fibrosis, also known as organ scarring, describes a pathological stiffening of organs or tissues caused by increased synthesis of extracellular matrix (ECM) components. In the past decades, mounting evidence has accumulated showing that the coagulation cascade is directly associated with fibrotic development. Recent findings suggest that, under inflammatory conditions, various cell types (e.g., immune cells) participate in the coagulation process causing pathological outcomes, including fibrosis. These findings highlighted the potential of anticoagulation therapy as a strategy in organ fibrosis. Indeed, preclinical and clinical studies demonstrated that the inhibition of blood coagulation is a potential intervention for the treatment of fibrosis across all major organs (e.g., lung, liver, heart, and kidney). In this review, we aim to summarize our current knowledge on the impact of components of coagulation cascade on fibrosis of various organs and provide an update on the current development of anticoagulation therapy for fibrosis.

Lipopeptide Pepducins as Therapeutic Agents

Pepducins are lipidated peptides that target the intracellular loops of G protein-coupled receptors (GPCRs) in order to modulate transmembrane signaling to internally located effectors. With a wide array of potential activities ranging from partial, biased, or full agonism to antagonism, pepducins represent a versatile class of compounds that can be used to potentially treat diverse human diseases or be employed as novel tools to probe complex mechanisms of receptor activation and signaling in cells and in animals. Here, we describe a number of different pepducins including an advanced compound, PZ-128, that has successfully progressed through phase 2 clinical trials in cardiac patients demonstrating safety and efficacy in suppressing myonecrosis and arterial thrombosis.

Bilirubin Nanoparticles Protect Against Cardiac Ischemia/Reperfusion Injury in Mice

Background

Ischemia/reperfusion (I/R) injury causes overproduction of reactive oxygen species, which are the major culprits of oxidative stress that leads to inflammation, apoptosis, myocardial damage, and dysfunction. Bilirubin acts as a potent endogenous antioxidant that is capable of scavenging various reactive oxygen species. We have previously generated bilirubin nanoparticles (BRNPs) consisting of polyethylene glycol–conjugated bilirubin. In this study, we examined the therapeutic effects of BRNPs on myocardial I/R injury in mice.

Methods and Results

In vivo imaging using fluorophore encapsulated BRNPs showed BRNPs preferentially targeted to the site of I/R injury in the heart. Cardiac I/R surgery was performed by first ligating the left anterior descending coronary artery. After 45 minutes, reperfusion was achieved by releasing the ligation. BRNPs were administered intraperitoneally at 5 minutes before and 24 hours after reperfusion. Mice that received BRNPs showed significant improvements in their cardiac output, assessed by echocardiogram and pressure volume loop measurements, compared with the ones that received vehicle treatment. BRNPs treatment also significantly reduced the myocardial infarct size in mice that underwent cardiac I/R, compared with the vehicle‐treatment group. In addition, BRNPs effectively suppressed reactive oxygen species and proinflammatory factor levels, as well as the amount of cardiac apoptosis.

Conclusions

Taken together, BRNPs could exert their therapeutic effects on cardiac I/R injury through attenuation of oxidative stress, apoptosis, and inflammation, providing a novel therapeutic modality for myocardial I/R injury.

Tissue factor cytoplasmic domain exacerbates post-infarct left ventricular remodeling via orchestrating cardiac inflammation and angiogenesis

The coagulation protein tissue factor (TF) regulates inflammation and angiogenesis via its cytoplasmic domain in infection, cancer and diabetes. While TF is highly abundant in the heart and is implicated in cardiac pathology, the contribution of its cytoplasmic domain to post-infarct myocardial injury and adverse left ventricular (LV) remodeling remains unknown.

Methods: Myocardial infarction was induced in wild-type mice or mice lacking the TF cytoplasmic domain (TF∆CT) by occlusion of the left anterior descending coronary artery. Heart function was monitored with echocardiography. Heart tissue was collected at different time-points for histological, molecular and flow cytometry analysis.

Results: Compared with wild-type mice, TF∆CT had a higher survival rate during a 28-day follow-up after myocardial infarction. Among surviving mice, TF∆CT mice had better cardiac function and less LV remodeling than wild-type mice. The overall improvement of post-infarct cardiac performance in TF∆CT mice, as revealed by speckle-tracking strain analysis, was attributed to reduced myocardial deformation in the peri-infarct region. Histological analysis demonstrated that TF∆CT hearts had in the infarct area greater proliferation of myofibroblasts and better scar formation. Compared with wild-type hearts, infarcted TF∆CT hearts showed less infiltration of proinflammatory cells with concomitant lower expression of protease-activated receptor-1 (PAR1) - Rac1 axis. In particular, infarcted TF∆CT hearts displayed markedly lower ratios of inflammatory M1 macrophages and reparative M2 macrophages (M1/M2). In vitro experiment with primary macrophages demonstrated that deletion of the TF cytoplasmic domain inhibited macrophage polarization toward the M1 phenotype. Furthermore, infarcted TF∆CT hearts presented markedly higher peri-infarct vessel density associated with enhanced endothelial cell proliferation and higher expression of PAR2 and PAR2-associated pro-angiogenic pathway factors. Finally, the overall cardioprotective effects observed in TF∆CT mice could be abolished by subcutaneously infusing a cocktail of PAR1-activating peptide and PAR2-inhibiting peptide via osmotic minipumps.

Conclusions: Our findings demonstrate that the TF cytoplasmic domain exacerbates post-infarct cardiac injury and adverse LV remodeling via differential regulation of inflammation and angiogenesis. Targeted inhibition of the TF cytoplasmic domain-mediated intracellular signaling may ameliorate post-infarct LV remodeling without perturbing coagulation.

Rivaroxaban attenuates cardiac hypertrophy by inhibiting protease-activated receptor-2 signaling in renin-overexpressing hypertensive mice

Rivaroxaban (Riv), a direct factor Xa (FXa) inhibitor, exerts anti-inflammatory effects in addition to anticoagulation. However, its role in cardiovascular remodeling is largely unknown. We tested the hypothesis that Riv attenuates the progression of cardiac hypertrophy and fibrosis induced by continuous activation of the renin-angiotensin system (RAS) in renin-overexpressing hypertensive transgenic (Ren-Tg) mice. We treated 12-week-old male Ren-Tg and wild-type (WT) mice with a diet containing Riv (12 mg/kg/day) or a regular diet for 4 weeks. After this, FXa in plasma significantly increased in Ren-Tg mice compared with WT mice, and Riv inhibited this increase. Left ventricular wall thickness (LVWT) and the area of cardiac fibrosis evaluated by Masson's trichrome staining were greater in Ren-Tg mice than in WT mice, and Riv decreased them. Cardiac expression levels of the protease-activated receptor (PAR)-2, tumor necrosis factor-α, transforming growth factor (TGF)-β1, and collagen type 3 α1 (COL3A1) genes were all greater in Ren-Tg mice than in WT mice, and Riv attenuated these increases. To investigate the possible involvement of PAR-2, we treated Ren-Tg mice with a continuous subcutaneous infusion of 10 μg/kg/day of the PAR-2 antagonist FSLLRY for 4 weeks. FSLLRY significantly decreased LVWT and cardiac expression of PAR-2, TGF-β1, and COL3A1. In isolated cardiac fibroblasts (CFs), Riv or FSLLRY pretreatment inhibited the FXa-induced increase in the phosphorylation of extracellular signal-regulated kinases. In addition, Riv or FSLLRY inhibited FXa-stimulated wound closure in CFs. Riv exerts a protective effect against cardiac hypertrophy and fibrosis development induced by continuous activation of the RAS, partly by inhibiting PAR-2.

Factor Xa Inhibition with Apixaban Does Not Influence Cardiac Remodelling in Rats with Heart Failure After Myocardial Infarction

BACKGROUND

Heart failure (HF) is considered to be a prothrombotic condition and it has been suggested that coagulation factors contribute to maladaptive cardiac remodelling via activation of the protease-activated receptor 1 (PAR1). We tested the hypothesis that anticoagulation with the factor Xa (FXa) inhibitor apixaban would ameliorate cardiac remodelling in rats with HF after myocardial infarction (MI).

METHODS AND RESULTS

Male Sprague-Dawley rats were either subjected to permanent ligation of the left ascending coronary artery (MI) or sham surgery. The MI and sham animals were randomly allocated to treatment with placebo or apixaban in the chow (150 mg/kg/day), starting 2 weeks after surgery. Cardiac function was assessed using echocardiography and histological and molecular markers of cardiac hypertrophy were assessed in the left ventricle (LV). Apixaban resulted in a fivefold increase in anti-FXa activity compared with vehicle, but no overt bleeding was observed and haematocrit levels remained similar in apixaban- and vehicle-treated groups. After 10 weeks of treatment, LV ejection fraction was 42 ± 3% in the MI group treated with apixaban and 37 ± 2 in the vehicle-treated MI group (p > 0.05). Both vehicle- and apixaban-treated MI groups also displayed similar degrees of LV dilatation, LV hypertrophy and interstitial fibrosis. Histological and molecular markers for pathological remodelling were also comparable between groups, as was the activity of signalling pathways downstream of the PAR1 receptor.

CONCLUSION

FXa inhibition with apixaban does not influence pathological cardiac remodelling after MI. These data do not support the use of FXa inhibitor in HF patients with the aim to amend the severity of HF. Graphical Abstract.

Cell type-specific roles of PAR1 in Coxsackievirus B3 infection

Protease-activated receptor 1 (PAR1) is widely expressed in humans and mice, and is activated by a variety of proteases, including thrombin. Recently, we showed that PAR1 contributes to the innate immune response to viral infection. Mice with a global deficiency of PAR1 expressed lower levels of CXCL10 and had increased Coxsackievirus B3 (CVB3)-induced myocarditis compared with control mice. In this study, we determined the effect of cell type-specific deletion of PAR1 in cardiac myocytes (CMs) and cardiac fibroblasts (CFs) on CVB3-induced myocarditis. Mice lacking PAR1 in either CMs or CFs exhibited increased CVB3 genomes, inflammatory infiltrates, macrophages and inflammatory mediators in the heart and increased CVB3-induced myocarditis compared with wild-type controls. Interestingly, PAR1 enhanced poly I:C induction of CXCL10 in rat CFs but not in rat neonatal CMs. Importantly, activation of PAR1 reduced CVB3 replication in murine embryonic fibroblasts and murine embryonic cardiac myocytes. In addition, we showed that PAR1 reduced autophagy in murine embryonic fibroblasts and rat H9c2 cells, which may explain how PAR1 reduces CVB3 replication. These data suggest that PAR1 on CFs protects against CVB3-induced myocarditis by enhancing the anti-viral response whereas PAR1 on both CMs and fibroblasts inhibits viral replication.

Deficiency of MMP1a (Matrix Metalloprotease 1a) Collagenase Suppresses Development of Atherosclerosis in Mice: Translational Implications for Human Coronary Artery Disease

[Figure: see text].

Chinese Herbs and Repurposing Old Drugs as Therapeutic Agents in the Regulation of Oxidative Stress and Inflammation in Pulmonary Diseases

Several pro-inflammatory factors and proteins have been characterized that are involved in the pathogenesis of inflammatory diseases, including acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, induced by oxidative stress, cytokines, bacterial toxins, and viruses. Reactive oxygen species (ROS) act as secondary messengers and are products of normal cellular metabolism. Under physiological conditions, ROS protect cells against oxidative stress through the maintenance of cellular redox homeostasis, which is important for proliferation, viability, cell activation, and organ function. However, overproduction of ROS is most frequently due to excessive stimulation of either the mitochondrial electron transport chain and xanthine oxidase or reduced nicotinamide adenine dinucleotide phosphate (NADPH) by pro-inflammatory cytokines, such as interleukin-1β and tumor necrosis factor α. NADPH oxidase activation and ROS overproduction could further induce numerous inflammatory target proteins that are potentially mediated via Nox/ROS-related transcription factors triggered by various intracellular signaling pathways. Thus, oxidative stress is considered important in pulmonary inflammatory processes. Previous studies have demonstrated that redox signals can induce pulmonary inflammatory diseases. Thus, therapeutic strategies directly targeting oxidative stress may be effective for pulmonary inflammatory diseases. Therefore, drugs with anti-inflammatory and anti-oxidative properties may be beneficial to these diseases. Recent studies have suggested that traditional Chinese medicines, statins, and peroxisome proliferation-activated receptor agonists could modulate inflammation-related signaling processes and may be beneficial for pulmonary inflammatory diseases. In particular, several herbal medicines have attracted attention for the management of pulmonary inflammatory diseases. Therefore, we reviewed the pharmacological effects of these drugs to dissect how they induce host defense mechanisms against oxidative injury to combat pulmonary inflammation. Moreover, the cytotoxicity of oxidative stress and apoptotic cell death can be protected via the induction of HO-1 by these drugs. The main objective of this review is to focus on Chinese herbs and old drugs to develop anti-inflammatory drugs able to induce HO-1 expression for the management of pulmonary inflammatory diseases.

Induction of HO-1 by 5, 8-Dihydroxy-4',7-Dimethoxyflavone via Activation of ROS/p38 MAPK/Nrf2 Attenuates Thrombin-Induced Connective Tissue Growth Factor Expression in Human Cardiac Fibroblasts

Heme oxygenase-1 (HO-1) has been shown to exert as an antioxidant and anti-inflammatory enzyme in cardiovascular inflammatory diseases. Flavonoids have been demonstrated to display anti-inflammatory and antioxidant effects through the induction of HO-1. 5,8-Dihydroxy-4',7-dimethoxyflavone (DDF), one of the flavonoid compounds, is isolated from Reevesia formosana. Whether DDF induced HO-1 expression on human cardiac fibroblasts (HCFs) remained unknown. Here, we found that DDF time- and concentration-dependently induced HO-1 protein and mRNA expression, which was attenuated by pretreatment with reactive oxygen species (ROS) scavenger N-acetyl cysteine (NAC) in HCFs. DDF-enhanced ROS generation was attenuated by NAC, but not by either diphenyleneiodonium chloride (DPI, Nox inhibitor) or MitoTempol (mitochondrial ROS scavenger). Interestingly, pretreatment with glutathione (GSH) inhibited DDF-induced HO-1 expression. The ratio of GSH/GSSG was time-dependently decreased in DDF-treated HCFs. DDF-induced HO-1 expression was attenuated by an inhibitor of p38 MAPK (p38i VIII) or siRNA, but not by MEK1/2 (PD98059) or JNK1/2 (SP600125). DDF-stimulated p38 MAPK phosphorylation was inhibited by GSH or p38i VIII. Moreover, DDF-induced HO-1 expression was mediated through Nrf2 phosphorylation and translocation into the nucleus which was attenuated by NAC or p38 siRNA. DDF also stimulated antioxidant response element (ARE) promoter activity which was inhibited by NAC, GSH, or p38i VIII. Interaction between Nrf2 and the ARE-binding sites on the HO-1 promoter was revealed by chromatin immunoprecipitation assay, which was attenuated by NAC, GSH, or p38i VIII. We further evaluated the functional effect of HO-1 expression on the thrombin-induced fibrotic responses. Our result indicated that the induction of HO-1 by DDF can attenuate the thrombin-induced connective tissue growth factor expression. These results suggested that DDF-induced HO-1 expression is, at least, mediated through the activation of the ROS-dependent p38 MAPK/Nrf2 signaling pathway in HCFs. Thus, the upregulation of HO-1 by DDF could be a candidate for the treatment of heart fibrosis.

PAR1 (Protease-Activated Receptor 1) Pepducin Therapy Targeting Myocardial Necrosis in Coronary Artery Disease and Acute Coronary Syndrome Patients Undergoing Cardiac Catheterization: A Randomized, Placebo-Controlled, Phase 2 Study

OBJECTIVE

Arterial thrombosis leading to ischemic injury worsens the prognosis of many patients with cardiovascular disease. PZ-128 is a first-in-class pepducin that reversibly inhibits PAR1 (protease-activated receptor 1) on platelets and other vascular cells by targeting the intracellular surface of the receptor. The TRIP-PCI (Thrombin Receptor Inhibitory Pepducin in Percutaneous Coronary Intervention) trial was conducted to assess the safety and efficacy of PZ-128 in patients undergoing cardiac catheterization with intent to perform percutaneous coronary intervention. Approach and Results: In this randomized, double-blind, placebo-controlled, phase 2 trial, 100 patients were randomly assigned (2:1) to receive PZ-128 (0.3 or 0.5 mg/kg), or placebo in a 2-hour infusion initiated just before the start of cardiac catheterization, on top of standard oral antiplatelet therapy. Rates of the primary end point of bleeding were not different between the combined PZ-128 doses (1.6%, 1/62) and placebo group (0%, 0/35). The secondary end points of major adverse coronary events at 30 and 90 days did not significantly differ but were numerically lower in the PZ-128 groups (0% and 2% in the PZ-128 groups, 6% and 6% with placebo, p=0.13, p=0.29, respectively). In the subgroup of patients with elevated baseline cardiac troponin I, the exploratory end point of 30-day major adverse coronary events + myocardial injury showed 83% events in the placebo group versus 31% events in the combined PZ-128 drug groups, an adjusted relative risk of 0.14 (95% CI, 0.02-0.75); P=0.02.

CONCLUSIONS

In this first-in-patient experience, PZ-128 added to standard antiplatelet therapy appeared to be safe, well tolerated, and potentially reduced periprocedural myonecrosis, thus providing the basis for further clinical trials. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02561000.

Protease-activated receptor 2 deficiency mediates cardiac fibrosis and diastolic dysfunction

AIMS

Heart failure with preserved ejection fraction (HFpEF) and pathological cardiac aging share a complex pathophysiology, including extracellular matrix remodelling (EMR). Protease-activated receptor 2 (PAR2) deficiency is associated with EMR. The roles of PAR1 and PAR2 have not been studied in HFpEF, age-dependent cardiac fibrosis, or diastolic dysfunction (DD).

METHODS AND RESULTS

Evaluation of endomyocardial biopsies from patients with HFpEF (n = 14) revealed that a reduced cardiac PAR2 expression was associated with aggravated DD and increased myocardial fibrosis (r = -0.7336, P = 0.0028). In line, 1-year-old PAR2-knockout (PAR2ko) mice suffered from DD with preserved systolic function, associated with an increased age-dependent α-smooth muscle actin expression, collagen deposition (1.7-fold increase, P = 0.0003), lysyl oxidase activity, collagen cross-linking (2.2-fold increase, P = 0.0008), endothelial activation, and inflammation. In the absence of PAR2, the receptor-regulating protein caveolin-1 was down-regulated, contributing to an augmented profibrotic PAR1 and transforming growth factor beta (TGF-β)-dependent signalling. This enhanced TGF-β/PAR1 signalling caused N-proteinase (ADAMTS3) and C-proteinase (BMP1)-related increased collagen I production from cardiac fibroblasts (CFs). PAR2 overexpression in PAR2ko CFs reversed these effects. The treatment with the PAR1 antagonist, vorapaxar, reduced cardiac fibrosis by 44% (P = 0.03) and reduced inflammation in a metabolic disease model (apolipoprotein E-ko mice). Patients with HFpEF with upstream PAR inhibition via FXa inhibitors (n = 40) also exhibited reduced circulating markers of fibrosis and DD compared with patients treated with vitamin K antagonists (n = 20).

CONCLUSIONS

Protease-activated receptor 2 is an important regulator of profibrotic PAR1 and TGF-β signalling in the heart. Modulation of the FXa/FIIa-PAR1/PAR2/TGF-β-axis might be a promising therapeutic approach to reduce HFpEF.

Silica nanoparticles induce JNK-mediated inflammation and myocardial contractile dysfunction

Increasing environmental exposure to silica nanoparticles (SiNPs) and limited cardiotoxicity studies posed a challenge for the safety evaluation and management of these materials. This study aimed to explore the adverse effects and underlying mechanisms of subacute exposure to SiNPs on cardiac function in rats. Results from echocardiographic, ultrastructural and histopathological analysis found that SiNPs induced cardiac contractile dysfunction, accompanied by incomplete myocardial structures, disordered sarcomere segments, interstitial edema and myocyte apoptosis in heart. Levels of myocardial enzymes and inflammatory factors were markedly increased in both serum and heart tissue, accompanied by elevated levels of oxidative damage occurred in the hearts of SiNPs-treated rats. SiNPs significantly upregulated the expressions of inflammation and contraction-related proteins, including JNK, p-JNK, c-Jun, TF and PAR1. Lentivirus transfection of JNK shRNA showed the low-expression of JNK-facilitated F-actin and inhibited TF in the SiNPs-treated cardiomyocytes. Moreover, SiNPs activated the mRNA and protein levels of JNK/TF/PAR1 pathway, and these effects were significantly dampened after JNK knock down. Our results demonstrate that SiNPs trigger myocardial contractile dysfunction via JNK/TF/PAR1 signaling pathway.

Blockade of PAR-1 Signaling Attenuates Cardiac Hypertrophy and Fibrosis in Renin-Overexpressing Hypertensive Mice

Background

Although PAR‐1 (protease‐activated receptor‐1) exerts important functions in the pathophysiology of the cardiovascular system, the role of PAR‐1 signaling in heart failure development remains largely unknown. We tested the hypothesis that PAR‐1 signaling inhibition has protective effects on the progression of cardiac remodeling induced by chronic renin–angiotensin system activation using renin‐overexpressing hypertensive (Ren‐Tg) mice.

Methods and Results

We treated 12‐ to 16‐week‐old male wild‐type (WT) mice and Ren‐Tg mice with continuous subcutaneous infusion of the PAR‐1 antagonist SCH79797 or vehicle for 4 weeks. The thicknesses of interventricular septum and the left ventricular posterior wall were greater in Ren‐Tg mice than in WT mice, and SCH79797 treatment significantly decreased these thicknesses in Ren‐Tg mice. The cardiac fibrosis area and monocyte/macrophage deposition were greater in Ren‐Tg mice than in WT mice, and both conditions were attenuated by SCH79797 treatment. Cardiac mRNA expression levels of PAR‐1, TNF‐α (tumor necrosis factor‐α), TGF‐β1 (transforming growth factor‐β1), and COL3A1 (collagen type 3 α1 chain) and the ratio of β‐myosin heavy chain (β‐MHC) to α‐MHC were all greater in Ren‐Tg mice than in WT mice; SCH79797 treatment attenuated these increases in Ren‐Tg mice. Prothrombin fragment 1+2 concentration and factor Xa in plasma were greater in Ren‐Tg mice than in WT mice, and both conditions were unaffected by SCH79797 treatment. In isolated cardiac fibroblasts, both thrombin and factor Xa enhanced ERK1/2 (extracellular signal‐regulated kinase 1/2) phosphorylation, and SCH79797 pretreatment abolished this enhancement. Furthermore, gene expression of PAR‐1, TGF‐β1, and COL3A1 were enhanced by factor Xa, and all were inhibited by SCH79797.

Conclusions

The results indicate that PAR‐1 signaling is involved in cardiac remodeling induced by renin–angiotensin system activation, which may provide a novel therapeutic target for heart failure.

Loss of Protease-Activated Receptor 4 Prevents Inflammation Resolution and Predisposes the Heart to Cardiac Rupture After Myocardial Infarction

BACKGROUND

Cardiac rupture is a major lethal complication of acute myocardial infarction (MI). Despite significant advances in reperfusion strategies, mortality from cardiac rupture remains high. Studies suggest that cardiac rupture can be accelerated by thrombolytic therapy, but the relevance of this risk factor remains controversial.

METHODS

We analyzed protease-activated receptor 4 (Par4) expression in mouse hearts with MI and investigated the effects of Par4 deletion on cardiac remodeling and function after MI by echocardiography, quantitative immunohistochemistry, and flow cytometry.

RESULTS

Par4 mRNA and protein levels were increased in mouse hearts after MI and in isolated cardiomyocytes in response to hypertrophic and inflammatory stimuli. Par4-deficient mice showed less myocyte apoptosis, reduced infarct size, and improved functional recovery after acute MI relative to wild-type (WT). Conversely, Par4^-/- mice showed impaired cardiac function, greater rates of myocardial rupture, and increased mortality after chronic MI relative to WT. Pathological evaluation of hearts from Par4^-/- mice demonstrated a greater infarct expansion, increased cardiac hemorrhage, and delayed neutrophil accumulation, which resulted in impaired post-MI healing compared with WT. Par4 deficiency also attenuated neutrophil apoptosis in vitro and after MI in vivo and impaired inflammation resolution in infarcted myocardium. Transfer of Par4^-/- neutrophils, but not of Par4^-/- platelets, in WT recipient mice delayed inflammation resolution, increased cardiac hemorrhage, and enhanced cardiac dysfunction. In parallel, adoptive transfer of WT neutrophils into Par4^-/- mice restored inflammation resolution, reduced cardiac rupture incidence, and improved cardiac function after MI.

CONCLUSIONS

These findings reveal essential roles of Par4 in neutrophil apoptosis and inflammation resolution during myocardial healing and point to Par4 inhibition as a potential therapy that should be limited to the acute phases of ischemic insult and avoided for long-term treatment after MI.

Cardioprotective Effects of Rivaroxaban on Cardiac Remodeling After Experimental Myocardial Infarction in Mice

Background: Direct-activated factor X (FXa) plays an important role in thrombosis and is also involved in inflammation via the protease-activated receptor (PAR)-1 and PAR-2 pathway. We hypothesized that rivaroxaban protects against cardiac remodeling after myocardial infarction (MI).

Methods and Results: MI was induced in wild-type mice by permanent ligation of the left anterior descending coronary artery. At day 1 after MI, mice were randomly assigned to the rivaroxaban and vehicle groups. Mice in the rivaroxaban group were provided with a regular chow diet plus rivaroxaban. We evaluated cardiac function by echocardiography, pathology, expression of mRNA and protein at day 7 after MI. Rivaroxaban significantly improved cardiac systolic function, decreased infarct size and cardiac mass compared with the vehicle. Rivaroxaban also downregulated the mRNA expression levels of tumor necrosis factor-α, transforming growth factor-β, PAR-1 and PAR-2 in the infarcted area, and both A-type and B-type natriuretic peptides in the non-infarcted area compared with the vehicle. Furthermore, rivaroxaban attenuated cardiomyocyte hypertrophy and the phosphorylation of extracellular signal-regulated kinase in the non-infarcted area compared with the vehicle.

Conclusions: Rivaroxaban protected against cardiac dysfunction in MI model mice. Reduction of PAR-1, PAR-2 and proinflammatory cytokines in the infarcted area may be involved in its cardioprotective effects.

Cardiac Expression of Factor X Mediates Cardiac Hypertrophy and Fibrosis in Pressure Overload

•

Factor X expression was increased in the heart following pressure overload and in isolated cardiac myocytes and fibroblasts.

•

Rivaroxaban treatment at doses that do not affect thrombin generation, blood coagulation or cardiac hemostasis attenuated cardiac inflammation, hypertrophy, and fibrosis caused by pressure overload and improved cardiac diastolic function.

•

Activated coagulation factor X induced PAR-1/-2–mediated elongated cardiomyocyte hypertrophy and PAR1-mediated cardiac fibroblast proliferation, migration and differentiation.

•

Activated coagulation factor X derived from a cardiac source may represent an important physiologic and pathophysiologic activator of PAR-1/PAR-2.

•

Non-anticoagulation dosage of rivaroxaban could provide an effective therapy to attenuate early phases of heart failure development.

Activated factor X is a key component of the coagulation cascade, but whether it directly regulates pathological cardiac remodeling is unclear. In mice subjected to pressure overload stress, cardiac factor X mRNA expression and activity increased concurrently with cardiac hypertrophy, fibrosis, inflammation and diastolic dysfunction, and responses blocked with a low coagulation-independent dose of rivaroxaban. In vitro, neurohormone stressors increased activated factor X expression in both cardiac myocytes and fibroblasts, resulting in activated factor X-mediated activation of protease-activated receptors and pro-hypertrophic and -fibrotic responses, respectively. Thus, inhibition of cardiac-expressed activated factor X could provide an effective therapy for the prevention of adverse cardiac remodeling in hypertensive patients.

Thrombin receptor PAR4 drives canonical NLRP3 inflammasome signaling in the heart

The deleterious effects of diabetes in the heart are increasingly attributed to inflammatory signaling through the NLRP3 (NOD, LRR and PYD domains-containing protein 3) inflammasome. Thrombin antagonists reduce cardiac remodeling and dysfunction in diabetic mice, in part by suppressing fibrin-driven inflammation. The role of cellular thrombin receptor subtypes in this context is not known. We sought to determine the causal involvement of protease-activated receptors (PAR) in inflammatory signaling of the diabetic heart. Mice with diet-induced diabetes showed increased abundance of pro-caspase-1 and pro-interleukin (IL)-1β in the left ventricle (LV), indicating transcriptional NLRP3 inflammasome priming, and augmented cleavage of active caspase-1 and IL-1β, pointing to canonical NLRP3 inflammasome activation. Caspase-11 activation, which mediates non-canonical NLRP3 inflammasome signaling, was not augmented. Formation of the plasma membrane pore-forming protein N-terminal gasdermin D (GDSMD), a prerequisite for IL-1β secretion, was also higher in diabetic vs. control mouse LV. NLRP3, ASC and IL-18 expression did not differ between the groups, nor did expression of PAR1 or PAR2. PAR3 was nearly undetectable. LV abundance of PAR4 by contrast increased with diabetes and correlated positively with active caspase-1. Genetic deletion of PAR4 in mice prevented the diet-induced cleavage of caspase-1, IL-1β and GDSMD. Right atrial appendages from patients with type 2 diabetes also showed higher levels of PAR4, but not of PAR1 or PAR2, than non-diabetic atrial tissue, along with increased abundance of cleaved caspase-1, IL-1β and GSDMD. Human cardiac fibroblasts maintained in high glucose conditions to mimic diabetes also upregulated PAR4 mRNA and protein, and increased PAR4-dependent IL-1β transcription and secretion in response to thrombin, while PAR1 and PAR2 expressions were unaltered. In conclusion, PAR4 drives caspase-1-dependent IL-1β production through the canonical NLRP3 inflammasome pathway in the diabetic heart, providing mechanistic insights into diabetes-associated cardiac thromboinflammation. The emerging PAR4-selective antagonists may provide a feasible approach to prevent cardiac inflammation in patients with diabetes.

Bioprofiles and mechanistic pathways associated with Cheyne-Stokes respiration: insights from the SERVE-HF trial

INTRODUCTION

The SERVE-HF trial included patients with heart failure and reduced ejection fraction (HFrEF) with sleep-disordered breathing, randomly assigned to treatment with Adaptive-Servo Ventilation (ASV) or control. The primary outcome was the first event of death from any cause, lifesaving cardiovascular intervention, or unplanned hospitalization for worsening heart failure. A subgroup analysis of the SERVE-HF trial suggested that patients with Cheyne-Stokes respiration (CSR) < 20% (low CSR) experienced a beneficial effect from ASV, whereas in patients with CSR ≥ 20% ASV might have been harmful. Identifying the proteomic signatures and the underlying mechanistic pathways expressed in patients with CSR could help generating hypothesis for future research.

METHODS

Using a large set of circulating protein-biomarkers (n = 276, available in 749 patients; 57% of the SERVE-HF population) we sought to investigate the proteins associated with CSR and to study the underlying mechanisms that these circulating proteins might represent.

RESULTS

The mean age was 69 ± 10 years and > 90% were male. Patients with CSR < 20% (n = 139) had less apnoea-hypopnea index (AHI) events per hour and less oxygen desaturation. Patients with CSR < 20% might have experienced a beneficial effect of ASV treatment (primary outcome HR [95% CI] = 0.55 [0.34-0.88]; p = 0.012), whereas those with CSR ≥ 20% might have experienced a detrimental effect of ASV treatment (primary outcome HR [95% CI] = 1.39 [1.09-1.76]; p = 0.008); p for interaction = 0.001. Of the 276 studied biomarkers, 8 were associated with CSR (after adjustment and with a FDR1%-corrected p value). For example, higher PAR-1 and ITGB2 levels were associated with higher odds of having CSR < 20%, whereas higher LOX-1 levels were associated with higher odds of CSR ≥ 20%. Signalling, metabolic, haemostatic and immunologic pathways underlie the expression of these biomarkers.

CONCLUSION

We identified proteomic signatures that may represent underlying mechanistic pathways associated with patterns of CSR in HFrEF. These hypothesis-generating findings require further investigation towards better understanding of CSR in HFrEF.

SUMMARY OF THE FINDINGS

PAR-1 proteinase-activated receptor 1, ADM adrenomedullin, HSP-27 heat shock protein-27, ITGB2 integrin beta 2, GLO1 glyoxalase 1, ENRAGE/S100A12 S100 calcium-binding protein A12, LOX-1 lectin-like LDL receptor 1, ADAM-TS13 disintegrin and metalloproteinase with a thrombospondin type 1 motif, member13 also known as von Willebrand factor-cleaving protease.

Effects of doxorubicin on the heart: From molecular mechanisms to intervention strategies

Cancer remains a major public health problem worldwide and was responsible for 9.6 million deaths in 2018. Oncologic treatments such as doxorubicin (Dox) and trastuzumab (Trz) are chemotherapeutic drugs used to treat several types of cancer, including solid and non-solid malignancies. Although these drugs have a significant impact on the reduction in mortality of cancer patients, this treatment has an adverse effect on the cardiovascular system. The mechanisms associated with Dox-induced cardiotoxicity involve inflammation, oxidative stress, apoptosis, mitochondria impairment and dysregulation of autophagy. Unfortunately, Trz, an effective anti-cancer drug, can potentiate these adverse effects. Trz is a recombinant DNA-derived humanized monoclonal antibody against human epidermal growth factor receptor 2 (HER2). Despite its high anti-cancer efficacy, Trz also has a cardiotoxic effect. Unlike Dox, this adverse effect of Trz on the heart is mostly reversible. A strategy to prevent this undesirable effect is urgently needed. Currently, several pharmacological interventions have shown promising results that might effectively attenuate Dox- and Trz-induced cardiac dysfunction. In this review, reports from in vitro, in vivo and clinical studies pertinent to the underlying mechanisms involved in chemotherapy-induced cardiotoxicity, are comprehensively summarized and discussed. In addition, the potential pharmacological interventions to prevent these cardiotoxic effects are described.

Platelets Are at the Nexus of Vascular Diseases

Platelets are important actors of cardiovascular diseases (CVD). Current antiplatelet drugs that inhibit platelet aggregation have been shown to be effective in CVD treatment. However, the management of bleeding complications is still an issue in vascular diseases. While platelets can act individually, they interact with vascular cells and leukocytes at sites of vascular injury and inflammation. The main goal remains to better understand platelet mechanisms in thrombo-inflammatory diseases and provide new lines of safe treatments. Beyond their role in hemostasis and thrombosis, recent studies have reported the role of several aspects of platelet functions in CVD progression. In this review, we will provide a comprehensive overview of platelet mechanisms involved in several vascular diseases.

p38α MAPK inhibition translates to cell cycle re-entry of neonatal rat ventricular cardiomyocytes and de novo nestin expression in response to thrombin and after apex resection

The present study tested the hypothesis that p38α MAPK inhibition leads to cell cycle re-entry of neonatal ventricular cardiomyocytes (NNVMs) and de novo nestin expression in response to thrombin and after apex resection of the neonatal rat heart. Thrombin (1 U/ml) treatment of 1-day old NNVMs did not induce cell cycle re-entry or nestin expression. Acute exposure of NNVMs to thrombin increased p38α MAPK and HSP27 phosphorylation and p38α/β MAPK inhibitor SB203580 abrogated HSP27 phosphorylation. Thrombin and SB203580 co-treatment of NNVMs led to bromodeoxyuridine incorporation and nestin expression. SB203580 (5 mg/kg) administration immediately after apex resection of 1-day old neonatal rat hearts and continued for two additional days shortened the fibrin clot length sealing the exposed left ventricular chamber. SB203580-treatment increased the density of troponin-T(+)-NNVMs that incorporated bromodeoxyuridine and expressed nuclear phosphohistone-3. Nestin(+)-NNVMs were selectively detected at the border of the fibrin clot and SB203580 potentiated the density that re-entered the cell cycle. These data suggest that the greater density of ventricular cardiomyocytes and nestin(+)-ventricular cardiomyocytes that re-entered the cell cycle after SB203580 treatment of the apex-resected neonatal rat heart during the acute phase of fibrin clot formation may be attributed in part to inhibition of thrombin-mediated p38α MAPK signalling.

Straight to the heart: Pleiotropic antiarrhythmic actions of oral anticoagulants

Mechanistic understanding of atrial fibrillation (AF) pathophysiology and the complex bidirectional relationship with thromboembolic risk remains limited. Oral anticoagulation is a mainstay of AF management. An emerging concept is that anticoagulants may themselves have potential pleiotropic disease-modifying effects. We here review the available evidence for hemostasis-independent actions of the oral anticoagulants on electrical and structural remodeling, and the inflammatory component of the vulnerable substrate.

Nonhemostatic Activities of Factor Xa: Are There Pleiotropic Effects of Anti-FXa Direct Oral Anticoagulants?

Factor Xa (FXa) is the key serine protease of the coagulation cascade as it is the point of convergence of the intrinsic and extrinsic pathways, leading to the formation of thrombin. Factor Xa is an established target of anticoagulation therapy, due to its central role in coagulation. Over the past years, several direct oral anticoagulants (DOACs) targeting FXa have been developed. Rivaroxaban, apixaban, and edoxaban are used in clinical practice for prevention and treatment of thrombotic diseases. Increasing evidence suggests that FXa exerts nonhemostatic cellular effects that are mediated mainly through protease-activated receptors-1 and -2 and are involved in pathophysiological conditions, such as atherosclerosis, inflammation, and fibrosis. Direct inhibition of FXa by DOACs could be beneficial in these conditions. This is a narrative review that focuses on the cellular effects of FXa in various cell types and conditions, as well as on the possible pleiotropic effects of FXa-targeting DOACs.

Direct oral anticoagulants and vitamin K antagonists are linked to differential profiles of cardiac function and lipid metabolism

BACKGROUND

Experimental data indicate that direct acting oral anticoagulants (DOAC) and vitamin K antagonists (VKA) may exert differential effects on cardiovascular disease.

METHODS

Data from the prospective, observational, single-center MyoVasc Study were used to examine associations of DOAC as compared to VKA with subclinical markers of cardiovascular disease, cardiac function, and humoral biomarkers in heart failure (HF).

RESULTS

Multivariable analysis adjusted for age, sex, traditional cardiovascular risk factors, comorbidities, and medications with correction for multiple testing demonstrated that DOAC therapy was among all investigated parameters an independent significant predictor of better diastolic function (E/E': β - 0.24 [- 0.36/- 0.12]; P < 0.0001) and higher levels of ApoA1 (β + 0.11 g/L [0.036/0.18]; P = 0.0038) compared to VKA therapy. In propensity score-weighted analyses, the most pronounced differences between DOAC and VKA-based therapy were also observed for E/E' (∆ - 2.36) and ApoA1 (∆ + 0.06 g/L). Sensitivity analyses in more homogeneous subsamples of (i) individuals with AF and (ii) individuals with asymptomatic HF confirmed the consistency and robustness of these findings. In the comparison of factor IIa and Xa-directed oral anticoagulation, no differences were observed regarding cardiac function (E/E' ratio: β_{IIa inhibitor} - 0.22 [- 0.36/- 0.08] vs. β_{Xa inhibitor} - 0.24 [- 0.37/- 0.11]) and lipid metabolism (ApoA1: β_{IIa inhibitor} 0.10 [0.01/0.18] vs. β_{Xa inhibitor} 0.12 [0.04/0.20]) compared to VKA therapy.

CONCLUSION

This study provides the first evidence for differential, non-conventional associations of oral anticoagulants on cardiac function and lipid metabolism in humans. The potentially beneficial effect of DOACs in the highly vulnerable population of HF individuals needs to be further elucidated and may have implications for individually tailored anticoagulation therapy.

Roles of Coagulation Proteases and PARs (Protease-Activated Receptors) in Mouse Models of Inflammatory Diseases

Activation of the blood coagulation cascade leads to fibrin deposition and platelet activation that are required for hemostasis. However, aberrant activation of coagulation can lead to thrombosis. Thrombi can cause tissue ischemia, and fibrin degradation products and activated platelets can enhance inflammation. In addition, coagulation proteases activate cells by cleavage of PARs (protease-activated receptors), including PAR1 and PAR2. Direct oral anticoagulants have recently been developed to specifically inhibit the coagulation proteases FXa (factor Xa) and thrombin. Administration of these inhibitors to wild-type mice can be used to determine the roles of FXa and thrombin in different inflammatory diseases. These results can be compared with the phenotypes of mice with deficiencies of either Par1 (F2r) or Par2 (F2rl1). However, inhibition of coagulation proteases will have effects beyond reducing PAR signaling, and a deficiency of PARs will abolish signaling from all proteases that activate these receptors. We will summarize studies that examine the roles of coagulation proteases, particularly FXa and thrombin, and PARs in different mouse models of inflammatory disease. Targeting FXa and thrombin or PARs may reduce inflammatory diseases in humans.

Are anticoagulants still indicated in pulmonary arterial hypertension?

Pulmonary arterial hypertension (PAH) is a type of pulmonary hypertension that is a progressive, fatal disease. Multiple underlying mechanisms for PAH have been identified, including vasoconstriction, intimal proliferation, medial hypertrophy, inflammation, mitochondrial dysfunction, and in situ thrombosis. Because it is an uncommon disease, it has been challenging to identify a specific treatment that targets the dominant disease mechanism in a given patient. Early success demonstrating that some patients (approximately 10%) possess pulmonary vasoreactivity at diagnosis has driven the development of pulmonary vasodilators as the mainstay of treatment. However, while they improve exercise tolerance in clinical trials, their effect on survival is limited. Therapies that target underlying disease mechanisms that affect a majority of patients are clearly needed if we are to significantly improve overall survival.

In the actual guidelines, chronic anticoagulation is no longer recommended in patients with idiopathic, hereditary, and drug-induced PAH although there is much indirect evidence for this.

There are data from over 40 years which include: (1) pathology studies showing the presence of thrombotic lesions in a majority of patients with PAH, both idiopathic and associated with many other conditions; (2) a similar frequency of thrombotic lesions in patients treated with pulmonary vasodilators as was seen in the years before their use; (3) mechanistic studies showing that procoagulant conditions predispose to the development of intraluminal thrombosis that contributes to vascular remodeling and the progressive nature of the pathologic changes; and (4) observational studies that, with one exception, have demonstrated a substantial survival advantage in patients with PAH treated with oral anticoagulation.

Acknowledging that no prospective randomized trial with anticoagulants has ever been done, we recommend a pragmatic approach to the use of anticoagulants in PAH. We suggest that the risks and benefits of chronic anticoagulation be considered in individual patients, and that warfarin be prescribed in patients with PAH, unless they have an increased risk of bleeding.

The question of whether direct oral anticoagulants (DOACs) would provide the same benefit as vitamin K antagonists is valid, but presently there are no data at all regarding their use in PAH. However, in patients with PAH in whom warfarin anticoagulation management proves problematic, it is reasonable to switch the patient to a DOAC as is current practice for other conditions.

Protease-activated receptor 1 activation enhances doxorubicin-induced cardiotoxicity

OBJECTIVE

The anti-cancer anthracycline drug Doxorubicin (Dox) causes cardiotoxicity. We investigated the role of protease-activated receptor 1 (PAR-1) in Dox-induced cardiotoxicity.

METHODS AND RESULTS

In vitro experiments revealed that PAR-1 enhanced Dox-induced mitochondrial dysfunction, reactive oxygen species and cell death of cardiac myocytes and cardiac fibroblasts. The contribution of PAR-1 to Dox-induced cardiotoxicity was investigated by subjecting PAR-1^-/- mice and PAR-1^+/+ mice to acute and chronic exposure to Dox. Heart function was measured by echocardiography. PAR-1^-/- mice exhibited significant less cardiac injury and dysfunction compared to PAR-1^+/+ mice after acute and chronic Dox administration. PAR-1^-/- mice had reduced levels of nitrotyrosine, apoptosis and inflammation in their heart compared to PAR-1^+/+ mice. Furthermore, inhibition of PAR-1 in wild-type mice with vorapaxar significantly reduced the acute Dox-induced cardiotoxicity.

CONCLUSION

Our results indicate that activation of PAR-1 contributes to Dox-induced cardiotoxicity. Inhibition of PAR-1 may be a new approach to reduce Dox-induced cardiotoxicity in cancer patients.

Evidence for functional PAR-4 thrombin receptor expression in cardiac fibroblasts and its regulation by high glucose: PAR-4 in cardiac fibroblasts

BACKGROUND

Thrombin promotes cardiac fibroblast proliferation and fibrosis via protease-activated receptor (PAR-1). PAR-4 is reportedly absent in cardiac fibroblasts. In smooth muscle cells, PAR-4 expression is also low but increases upon hyperglycemia and contributes to vascular remodelling in diabetic mice. We examined if PAR-4 is a glucose-responsive gene with remodelling-related functions in cardiac fibroblasts.

METHODS AND RESULTS

Cardiac PAR-4 increased in mice with streptozotocin- or diabetogenic diet (DD)-induced diabetes. PAR-4 mRNA and protein were detectable in cardiac fibroblasts from chow-fed mice and increased in high (HG, 25mM) vs. low glucose (LG; 5.5mM) cultures. Conversely PAR-4 mRNA was higher in fibroblasts from DD-fed mice but reduced in LG cultures. Cardiac fibroblasts in HG culture responded more strongly to thrombin or PAR-4 activating peptide in terms of migration (wound-scratch assay), remodelling-associated gene expression (interleukin 6, alpha smooth muscle actin) and oxidative stress (dihydroethidium fluorescence).

CONCLUSION

PAR-4 is expressed in mouse cardiac fibroblasts and is dynamically regulated by extracellular glucose in vitro and diabetes in vivo, thereby impacting on fibroblast functions relevant for cardiac remodelling. These findings add further evidence for the usefulness of the recently developed PAR-4 antagonists in clinical settings.

Argatroban Attenuates Diabetic Cardiomyopathy in Rats by Reducing Fibrosis, Inflammation, Apoptosis, and Protease-Activated Receptor Expression

PURPOSE

Chronic diabetes is associated with cardiovascular dysfunctions. Diabetic cardiomyopathy (DCM) is one of the serious cardiovascular complications associated with diabetes. Despite significant efforts in understanding the pathophysiology of DCM, management of DCM is not adequate due to its complex pathophysiology. Recently, involvement of protease-activated receptors (PARs) has been postulated in cardiovascular diseases. These receptors are activated by thrombin, trypsin, or other serine proteases. Expression of PAR has been shown to be increased in cardiac diseases such as myocardial infarction, viral myocarditis, and pulmonary arterial hypertension. However, the role of PAR in DCM has not been elucidated yet. Therefore, in the present study, we have investigated the role of PAR in the condition of DCM using a pharmacological approach. We used argatroban, a direct thrombin inhibitor for targeting PAR.

METHODS

Type-2 diabetes mellitus (T2DM) was induced by high-fat feeding along with low dose streptozotocin (STZ 35 mg/kg, i.p. single dose) in male Sprague-Dawley rats. After 16 weeks of diabetes induction, animals were treated with argatroban at 0.3 and 1 mg/kg dose daily for 4 weeks. After 20 weeks, ventricular functions were measured using ventricular catheterization. Cardiac histology, TUNEL staining, and immunoblotting were performed to evaluate cardiac fibrosis, DNA fragmentation, and expression level of different proteins, respectively.

RESULTS

T2DM was associated with cardiac structural and functional disturbances as evidenced from impaired cardiac functional parameters and increased fibrosis. There was a significant increase in PAR expression after 20 weeks of diabetes induction. Four weeks argatroban treatment ameliorated metabolic alterations (reduced plasma glucose and cholesterol), ventricular dysfunctions (improved systolic and diastolic functions), cardiac fibrosis (reduced percentage area of collagen in picro-sirius red staining), and apoptosis (reduced TUNEL positive nuclei). Reduced expression of PAR1 and PAR4 in the argatroban-treated group indicates a response towards inhibition of thrombin. In addition, AKT (Ser-473), GSK-3β (Ser-9), p-65 NFĸB phosphorylation, TGF-β, COX-2, and caspase-3 expression were reduced significantly along with an increase in SERCA expression in argatroban-treated diabetic rats which indicated the anti-fibrotic, anti-inflammatory, and anti-apoptotic potential of argatroban in DCM.

CONCLUSION

This study suggests the ameliorative effects of argatroban in diabetic cardiomyopathy by improving ventricular functions and reducing fibrosis, inflammation, apoptosis, and PAR expression.

Attenuation of type-1 diabetes-induced cardiovascular dysfunctions by direct thrombin inhibitor in rats: a mechanistic study

Chronic diabetes is associated with ventricular dysfunctions in the absence of hypertension and coronary artery diseases. This condition is termed as diabetic cardiomyopathy (DCM). There is no favourable treatment available for the management of diabetic cardiomyopathy. Recent studies have reported increase in circulating thrombin level among diabetic patients which is responsible for hypercoagulability of blood. Thrombin induces inflammation and fibrosis, and enhances cardiac cell growth and contractility in vitro. In this study, we have investigated the effects of argatroban; a direct thrombin inhibitor against DCM in streptozotocin-induced type-1 diabetes. Diabetes was induced by single dose of streptozotocin (STZ; 50 mg/kg, i.p.) in male Sprague-Dawley rats. After 4 weeks of diabetes induction, the animals were treated with argatroban (0.3 and 1 mg/kg, i.p. daily) for the next 4 weeks. The effect of argatroban was evaluated against diabetes-associated cardiac dysfunction, structural alteration and protein expression. STZ-induced diabetic rats exhibited significant decline in left ventricular functions. Four weeks of treatments with argatroban significantly improved ventricular functions without affecting heart rate. Further, it also protected heart against structural changes induced by diabetes as shown by reduction in fibrosis, hypertrophy and apoptosis. The improvement in cardiac functions and structural changes was associated with significant reduction in left ventricular expression of thrombin receptor also termed as protease-activated receptor-1 or PAR1, p-AKT (ser-473), p-50 NFκB and caspase-3 proteins. This study demonstrates beneficial effects of argatroban via improvement in cardiac functions and structural changes in STZ-induced DCM. These effects may be attributed through reduction in cardiac inflammation, fibrosis and apoptosis.